Chromospheric Macrospicules: Connection to the Solar Dynamo?

Introduction: This study aims to provide further evidence for the potential influence of the global solar magnetic field on localized chromospheric jets, the macrospicules (MS). Macrospicules are localized small-scale jet-like phenomena in the solar atmosphere, which have the potential to transport a considerable amount of momentum and energy from the lower solar atmospheric regions to the transition region and the low corona. Methods: Using state-of-the-art spatial and temporal resolution observations yielded by the Atmospheric Imaging Assembly of Solar Dynamics Observatory, we constructed a database covering a seven-year-long period, containing 358 macrospicules that occurred between June 2010 and June 2017, detected at 30.4 nm wavelength. The results are based on the long-term variation of the height, length, average speed, and width of MS in coronal holes [CH-MS] and in Quiet Sun [QS-MS] areas both in the northern and southern hemispheres of the Sun. Results: Three of the five timesets of the investigated physical properties of MS show a clear long-term temporal variation. Wavelet analyses of the temporal variation of maximum length, maximum area, and average velocity reveal a strong pattern of periodicities at around 2 years. A comparison with solar activity proxies also uncovers that the minima and maxima of quasi-biennial oscillations [QBOs] of MS properties and solar activity proxies occur at around the same epoch. Spatially, the characteristic values of these parameters are found to be slightly greater for QS-MS than for CH-MS all around the solar disk. We have also discovered evidence towards supporting the hypothesis that there is a connection between the migration pattern of the formation cradle of MS and the nearly two-year-long oscillations. Furthermore, MS tend to exhibit parabolic motion, which indicates the strong effect of gravity. We have modelled this motion of MS in the atmosphere